The present invention relates to a motor vehicle equipped with a so-called xe2x80x9chands-freexe2x80x9d access system.
In a system such as this, a recognition device, sometimes also known as an identification device, is installed on the vehicle to operate the means for locking the doors or other opening leaves of the vehicle, this recognition device being capable of remotely exchanging data with an identification member, sometimes also called an xe2x80x9cidentifierxe2x80x9d, worn or carried by a user to allow access to the vehicle when the identification member has been authenticated by the recognition device. To allow dialog between the recognition device and the identification member, several antennas are generally distributed around the periphery of the vehicle so as to detect the presence of the identification member outside the vehicle. Such antennas are, for example, arranged in the external rear-view mirrors, the door handles, the door posts, etc. When the user has commanded locking of the doors of the vehicle, for example by pressing a button provided for this purpose on the external door handle and has moved away from the vehicle, the system automatically locks the doors and other opening leaves of the vehicle as soon as the user wearing or carrying the identification member has left the zone of coverage of said external antennas.
Furthermore, such a system can also inhibit vehicle engine electronic immobilizer devices when somebody equipped with an identification member giving him clearance to drive the vehicle is inside the cabin of the vehicle. In this case, the antennas are arranged, for example, on the dashboard, in the seats of the vehicle or on the interior walls of the doors.
However, the number of antennas to be fitted in the vehicle becomes high, which increases the cost and time taken to fit the system in the vehicle.
This is why the current Applicant Company has already proposed a motor vehicle equipped with a so-called xe2x80x9chands-freexe2x80x9d access system of the abovementioned kind comprising at least one pair of antennas placed one along each side of the vehicle, the two antennas having a common zone of coverage covering the interior of the vehicle so that the recognition device is capable of detecting the presence of an identification member in said common zone of coverage when said pair of antennas receives a signal from that same identification member, each antenna of said pair of antennas also having its own zone of coverage outside the vehicle so that the recognition device is capable of detecting the presence of an identification member in one of the two individual zones of coverage when the associated antenna is the only one to receive a signal from the identification member.
However, in order to achieve a range of the order of 2 m outside the vehicle, it is sometimes necessary to power the antennas with a relatively high nominal electrical power. This is the case in particular when the antennas are fitted inside the cabin, for example in the internal lining of the door posts. When this is the case, it may be that when the recognition device sends out an interrogation signal via the two antennas, the zone of coverage of each antenna, that is to say the zone in which they can detect an identification member worn or carried by a user, extends on each side of the vehicle as illustrated in FIG. 1 of the attached drawings.
Reference is made to this FIG. 1. This shows a vehicle V equipped with a so-called xe2x80x9chands-freexe2x80x9d access system which comprises a recognition device 1 connected to two antennas 2 and 3 arranged one on the right-hand side and one on the left-hand side of the vehicle V, for example in the internal linings of the B-pillars 4 and 5 located respectively between the right-hand doors 6 and 7 and between the left-hand doors 8 and 9 of said vehicle. FIG. 1 also depicts, in dashed line, the zones of coverage Z1 and Z2 of the two antennas 2 and 3 when they are powered at nominal power. Each of the two zones extends on both sides of the vehicle V. In consequence, if the user wearing or carrying an identification member 11 is in the position depicted in FIG. 1, near the antenna 3, he is detected both by the antenna 3 and by the antenna 2. This may be troublesome if there is a desire to have selective detection of the identification number 11 according to whether it is located on one side of the vehicle V or the other. Such selectivity is advantageous because it makes it possible, when the antenna 2 located on the right-hand side or passenger side detects an authorized user approaching the vehicle from this side, to cause, for example, the unlocking of the locks of the doors on just the passenger side, and when the antenna 3 located on the left-hand side or the driver side detects an authorized driver of the vehicle approaching the latter from the driver side, to bring about the unlocking of the locks of the doors only on the driver side (or both sides) and, in addition, other functions such as preheating the engine in the case of a diesel engine, for example.
In order to overcome this problem of selectivity, the electrical power of the signal supplied to the antennas 2 and 3 could be reduced so as to reduce their range or zone of coverage so that each antenna radiated to the outside of the vehicle V only on the side of the antenna concerned. However, such a solution would obviously lead to a significant and undesired reduction in the range of each antenna toward the outside of the motor vehicle.
The object of the present invention is therefore to provide a solution to the aforementioned problem of selectivity in the case where the zone of coverage or detection zone of each of the two antennas extends on both sides of the motor vehicle.
To this end, the present invention provides a motor vehicle equipped with a recognition device for operating means for locking the opening leaves of the motor vehicle, said recognition device being capable of remotely exchanging data with an identification member worn or carried by a user, to allow access to the vehicle when the identification member has been authenticated by the recognition device, the latter being connected to a pair of antennas placed one along each side of the vehicle and each having, when powered at nominal power, a zone of coverage which covers the interior of the cabin of the vehicle and extends laterally to the outside at least on the side on which the antenna is located, so as to allow a dialog between the recognition device and the identification member when the latter is located in the zone of coverage of at least one of said antennas, wherein the recognition device is capable, in response to the action of the user on an external member placed on one side of the vehicle, of causing the antenna located on the same side as said external member to be powered at said nominal power and the antenna located on the opposite side of the vehicle to be powered at a reduced power so that the latter antenna has a reduced zone of coverage extending toward the outside of the vehicle only on said side opposite the one on which this antenna is located.
In consequence, only the antenna which is powered at nominal power and which is located on the same side as the external member on which the user has acted will be capable of detecting the possible presence of an authorized identification member outside the vehicle on the same side as said external member on which the user has acted.
As a preference, the powering of one of the two antennas at nominal power and the powering of the other antenna at reduced power are offset in time.
As a preference, the pair of antennas is placed approximately in the middle of the sides of the vehicle.
For example, said pair of antennas may be installed in the door handles or in the B-pillars of the vehicle bodywork.
Said external member may be an external door handle or pushbutton on which the user acts to request the locking or unlocking of the door locks.